1. Field
Embodiments relate to a water level sensing apparatus to sense a level of supplied water, a water supply hose and a washing machine having the same.
2. Description of the Related Art
In general, a level or an amount of water supplied to a washing machine or a dishwasher is important in operation of the washing machine or the dishwasher. For example, in case of a washing machine, an amount of water corresponding to an amount of laundry to be washed needs to be supplied so as to perform effective washing. That is, when the amount of supplied water is smaller than the amount of laundry to be washed, washing is not effectively carried out, and when the amount of supplied water is greater than the amount of laundry to be washed, a large amount of water is unnecessarily consumed and an excessively large amount of power is consumed due to consumption of the large amount of water. In order to supply the amount of water corresponding to the amount of the laundry to be washed, a water level within a tub of the washing machine needs to be precisely sensed.
Water level sensing methods generally include a water level sensing method using a mechanical water level sensing apparatus and a water level sensing method using a semiconductor pressure sensor. These water level sensing methods applied to a washing machine will be described as follows.
First, the water level sensing method using the mechanical water level sensing apparatus will be described. When a water level within a tub of a washing machine is raised due to water supplied to the inside of the tub, an air pressure between a water surface within a connection hose and the water level sensing apparatus is increased. The increased air pressure pushes a diaphragm of the mechanical water level sensing apparatus upward, and then the diaphragm pushes a core upward. A magnetic flux density value is varied by interaction between the core and a bobbin surrounding the core. The magnetic flux density value resonates together with a capacitance value in an operating circuit and is output as a frequency. An output frequency value is varied due to the magnetic flux density value varied according to the water level, and the water level within the tub of the washing machine is judged thereby.
Next, the water level sensing method using the semiconductor pressure sensor will be described. The semiconductor pressure sensor includes a diaphragm to which a strain gauge is attached. In the same manner as the water level sensing apparatus using the core and the bobbin, the diaphragm is deformed by variation of an air pressure and the strain gauge measures such deformation of the diaphragm, thereby measuring a water level.
The above-described conventional water level sensing apparatuses are repeatedly driven by mechanical operation, thus having low durability. Further, the conventional water level sensing apparatuses are operated by the received air pressure and have great water level variation due to change of a volume within the hose and change of an air density, thus unnecessarily wasting water and power.